CN116117174A

CN116117174A - Apparatus and method for laser-based powder bed fusion

Info

Publication number: CN116117174A
Application number: CN202310219806.9A
Authority: CN
Inventors: 叶佐元
Original assignee: Divergent Technologies Inc
Current assignee: Divergent Technologies Inc
Priority date: 2018-03-07
Filing date: 2019-03-05
Publication date: 2023-05-16
Also published as: EP3762167A4; US20190275612A1; US11224943B2; CN112118926A; WO2019173363A1; CN112118926B; US20220097174A1; EP3762167A1

Abstract

Apparatus and methods for laser-based powder bed fusion are provided. The apparatus includes a depositor that deposits multiple layers of powder material, a laser beam source that generates a laser beam having a variable beam geometry, and a beam shaping component that shapes the laser beam into one of a plurality of beam geometries to fuse the powder material.

Description

Apparatus and method for laser-based powder bed fusion

The present application is a divisional application of application number 201980029955.0 (international application number PCT/US 2019/020789), entitled "variable beam geometry based laser powder bed fusion".

Cross Reference to Related Applications

The present application claims the benefit of U.S. patent application Ser. No.15/914,874, entitled "VARIABLE BEAM GEOMETRY LASER-BASED POWDER BED FUSION," filed 3/7 of 2019, the contents of which are expressly incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates generally to additive manufacturing, and more particularly to variable beam geometry laser-based powder bed fusion.

Background

Powder Bed Fusion (PBF) systems can produce metal structures (referred to as constructs) having geometrically complex shapes, including shapes that are difficult or impossible to produce using conventional manufacturing processes. The PBF system includes Additive Manufacturing (AM) techniques for producing the build up layer by layer. Each layer or slice may be formed by the following process: a layer of metal powder is deposited and then a region of the metal powder layer that corresponds to the cross-section of the build member in that layer is fused (e.g., melted and cooled). This process may be repeated to form the next slice of the build member, and so on, until the build member is complete. Because each layer is deposited on top of the previous layer, the PBF can be compared to forming the structure slice by slice from the bottom.

The laser-based PBF can be used to fabricate complex geometries and reduce custom cost. Unfortunately, manufacturing with a laser-based PBF system can be a slow process compared to the processes that may be required for mass production. The application of high power laser systems in current PBF systems may result in evaporation of material during the printing process, thereby increasing manufacturing costs.

Disclosure of Invention

Several aspects of variable beam geometry based laser-based PBFs and systems and methods of fabrication therewith are described more fully below.

In one aspect of the disclosure, an apparatus for laser-based powder bed fusion is presented. The apparatus includes a depositor that deposits multiple layers of powder material. The apparatus also includes a laser beam source that generates a laser beam having a variable beam geometry. The apparatus further includes a laser application component (e.g., a deflector) that applies a laser beam in one of a plurality of beam geometries to fuse the powder material.

In another aspect of the present disclosure, a method of laser-based powder bed fusion is presented. The method includes adjusting a laser beam geometry to form an adjusted laser beam comprising a line or two-dimensional shape. The method further includes applying an adjusted laser beam to at least a portion of the powder material to scan at least a portion of the defined build member.

Other aspects will become readily apparent to those skilled in the art from the following detailed description, wherein only a few exemplary embodiments are shown and described by way of illustration. As will be realized by those skilled in the art, the concepts described herein are capable of other and different embodiments and their several details are capable of modification in various other respects, all without departing from the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

Drawings

In the drawings, various aspects of the concepts described herein will now be presented in the detailed description by way of example and not limitation, wherein:

figures 1A-1D show respective side views of an exemplary PBF system during different stages of operation.

Fig. 2A and 2B are diagrams illustrating exemplary beam shaping components that are operated to change the geometry of a laser beam in accordance with aspects of the present disclosure.

Fig. 3 is a diagram illustrating an exemplary L-PBF system for scanning a build in accordance with aspects of the present disclosure.

Fig. 4 illustrates an exemplary adjustment of a laser beam during scanning in accordance with aspects of the present disclosure.

Fig. 5 is a diagram illustrating an example energy flux level configuration of a laser beam adjusted for 2-D scanning in accordance with aspects of the present disclosure.

Fig. 6 is a flow chart of an exemplary method of configuring a laser beam in an L-PBF device to scan a build member.

Detailed Description

The detailed description set forth below in connection with the appended drawings is intended to provide a description of various exemplary embodiments of the concepts disclosed herein and is not intended to represent the only embodiments in which the present disclosure may be practiced. The term "exemplary" used in this disclosure means "serving as an example, instance, or illustration," and should not necessarily be construed as preferred or advantageous over other embodiments set forth in the disclosure. The detailed description includes specific details for the purpose of providing a thorough and complete disclosure of the scope of the concepts that will fully convey the concept to those skilled in the art. However, the present disclosure may be practiced without these specific details. In some instances, well-known structures and components may be shown in block diagram form or omitted entirely in order to avoid obscuring the various concepts presented throughout this disclosure.

While the present disclosure is generally directed to laser-based PBF (L-PBF) systems, it should be understood that such L-PBF systems may encompass a variety of AM technologies. Thus, the L-PBF process may include, inter alia, the following printing techniques: direct Metal Laser Sintering (DMLS), selective Laser Melting (SLM), and Selective Laser Sintering (SLS). Other PBF processes relevant to the principles of the present disclosure include those presently contemplated or under commercial development. Although specific details of each such process are omitted to avoid unduly obscuring the key concepts of the present disclosure, it is to be understood that the claims are intended to cover such technology and related structures.

L-PBF systems can produce metal and polymer structures (called constructs) having geometrically complex shapes, including shapes that are difficult or impossible to produce using conventional manufacturing processes. The L-PBF system generates the constructs layer-by-layer (i.e., slice-by-slice). Each slice may be formed by the following process: a layer of metal powder is deposited and fused (e.g., melted and cooled) to a region of the metal powder layer that corresponds to the cross-section of the build member in the slice. This process may be repeated to form the next slice of the build, and so on, until all layers are deposited and the build is complete.

Aspects of the present disclosure are directed to laser spot geometry for laser-based PBF (L-PBF) systems, which can increase build rate and provide flexibility and additional control of the manufacturing process. The laser spot is the area of the surface illuminated by the laser. Instead of using a laser beam configured to terminate in a tiny, nearly punctiform spot (the spot having a small diameter that remains constant over time), the laser beam may instead be configured to use a variable beam or spot geometry. For example, the beam geometry (i.e., the area of the surface of the printed material that is irradiated by the laser) may be a line, square, rectangle, triangle, asymmetric shape, or any other two-dimensional shape. The identified beam geometry may then be applied to the surface of the printing material using a two-dimensional scan. In so doing, the laser beam may be applied in a PBF printing operation so that a larger continuous area of the powder bed may be processed at any given time. In an embodiment, the beam geometry may be dynamically altered during a 3-D printing operation. Thus, for example, an L-PBF 3-D printer may utilize a corresponding large beam geometry to fuse larger areas, and subsequently or periodically, the 3-D printer may alter the beam geometry to smaller lines or a common punctual shape to scan corner portions of an object and/or fuse details of a build member on a smaller scale.

According to aspects of the present disclosure, the laser beam geometry may be adjusted based on the geometry of the object (build member) to be produced. The laser beam geometry may be dynamically adjusted at the beginning of a scan, on a slice-by-slice basis, at a specified time within a slice, or on the fly. Furthermore, the laser beam geometry may also be continuously varied as the laser scans through the powder bed, for example, with variations consistent with the conceptual structure of the object identified in the Computer Aided Design (CAD) profile.

The use of variable beam geometry may advantageously increase the throughput of the L-PBF process. Furthermore, adjusting the beam geometry as described herein may allow laser power to be applied to the powder bed over a larger area, which means that the energy flux may be kept small to reduce material evaporation. Furthermore, the energy distribution of the spot geometry can be adjusted according to the scan vector (direction of scan) to provide heating and cooling rate control, taking into account the two-dimensional nature of the adjusted laser spot geometry. Controlling the cooling rate during the curing process may allow for reducing thermal stresses and altering the microstructure of the final part to achieve desired material properties.

Fig. 1A-1D illustrate respective side views of an exemplary laser-based PBF (L-PBF) system 100 during different stages of operation. As described above, the particular embodiment shown in fig. 1A-1D is one of many applicable examples of L-PBF systems employing the principles of the present disclosure. It should also be noted that the elements of fig. 1A-1D, as well as other figures in this disclosure, are not necessarily drawn to scale, but may be drawn larger or smaller for the purpose of better illustrating the concepts described herein. The L-PBF system 100 may include: a depositor 101 that may deposit each layer of powder material; a laser beam source 103 that can generate a laser beam; a beam shaping component 104 that can shape the laser beam according to a selected beam geometry; a deflector 105 which can apply a laser beam in the form of a selected beam geometry to fuse the powder material; and build plate 107, which may support one or more build members, such as build member 109.

The L-PBF system 100 may also include a build floor 111 positioned within the powder bed vessel. The walls 112 of the powder bed container may generally define the boundaries of the powder bed container defined between the side walls 112 and a portion of the underlying build floor 112. Build plate 111 may gradually lower build plate 107 so that depositor 101 may deposit the next layer of powder material. The L-PBF system 100 may additionally include a chamber 113 that may house other components of the L-PBF system 100 (e.g., the laser beam source 103, the beam shaping component 104, and the deflector 105) to protect these other components, achieve environmental and temperature regulation, and mitigate contamination risks. In addition, the PBF system 100 may include a temperature sensor 122 to monitor the ambient temperature, the temperature of the powder material 117, and/or the temperature of components of the L-PBF system 100. For example, the depositor 101 may include a feeder 115 that holds a powder 117 (such as a metal powder). The depositor 101 may also include a leveler 119 that may level the top of each layer of deposited powder (see, e.g., the powder layer 125 of fig. 1C) by displacing the deposited powder 117 over a predetermined layer height (e.g., corresponding to the powder layer thickness 123 of fig. 1B).

Referring specifically to FIG. 1A, there is shown an L-PBF system 100 after fusing of the cut pieces of build member 109 but before deposition of the next layer of powder 117. In fact, FIG. 1A shows the time when the L-PBF system 100 has deposited and fused slices in multiple layers (e.g., 150 layers) to form the current state of the build member 109 (e.g., formed from 150 slices). The plurality of layers that have been deposited create a powder bed 121 that includes deposited but unfused powder.

Fig. 1B shows the L-PBF system 100 in a stage in which the build-up floor 111 may be reduced by a powder layer thickness 123. The lowering of the build floor 111 causes the build member 109 and the powder bed 121 to drop by a powder layer thickness 123 such that the top of the build member and the powder bed is lower than the top of the powder bed vessel wall 112 by an amount equal to the powder layer thickness. For example, in this way, a space with a constant thickness equal to the powder layer thickness 123 can be created on top of the build member 109 and the powder bed 121.

Fig. 1C shows the L-PBF system 100 in a stage in which the depositor 101 is positioned to deposit powder 117 in a space formed on the top surface of the build member 109 and powder bed 121 and bounded by the powder bed container wall 112. In this example, the depositor 101 is gradually moved over a defined space while releasing the powder 117 from the feeder 115. The leveler 119 may level the released powder to form a powder layer 125 having a thickness approximately equal to the powder layer thickness 123 (see fig. 1B). Thus, the powder 117 in the L-PBF system 100 may be supported by a powder material support structure, which may include, for example, build plate 107, build floor 111, build member 109, wall 112, and the like. It should be noted that the thickness of the illustrated powder layer 125 (e.g., powder layer thickness 123 of fig. 1B) may be greater than the actual thickness used to exemplarily contain 150 previously deposited layers as described above with reference to fig. 1A.

Fig. 1D shows L-PBF system 100 after deposition of powder layer 125 (fig. 1C) to generate a next slice in build member 109. Referring to fig. 1D, the laser beam source 103 may generate a laser beam. The beam shaping component 104 can be used to change the geometry of the laser beam to the form of a line, square, rectangle, or other two-dimensional shape. In some aspects, the beam shaping component 104 can shape the laser beam through a phase plate and free space propagation. The beam shaping component 104 may include a plurality of diffractive, reflective and refractive devices, such as diffractive beam splitters, diffractive diffusers, phase plates, lenses, mirrors, or other optical elements. The change in size and geometry of the laser beam 127 may be achieved, for example, by motorized displacement of the optical elements of the beam shaping part 104, as discussed further below with reference to fig. 2A-2B. In some aspects, the geometry of the beam shape may be set according to the construct 109. The geometry of the beam shape may be modified on a slice-by-slice basis based on the geometry of the build member to reduce the scan time of a particular layer. In some aspects, the geometry of the beam shape may also be modified at the intermediate layer, or even continuously altered throughout the scan of the build member 109.

The deflector 105 may apply a laser beam 127 of a selected geometry to fuse the next slice in the build member 109. In various embodiments, the deflector 105 may include one or more gimbals and actuators that may rotate and/or translate the laser beam source 103 and/or the beam shaping component 104 to position the laser beam 127. In various embodiments, the laser beam source 103, the beam shaping component 104, and/or the deflector 105 may modulate the laser beam, e.g., turn the laser beam on and off as the deflector scans, so that the laser beam is applied only to the appropriate areas of the powder layer. For example, in various embodiments, the laser beam may be modulated by a Digital Signal Processor (DSP).

As shown in fig. 1D, most of the fusion of the powder layer 125 occurs in the area of the powder layer on top of the previous slice (i.e., previously fused powder). An example of such a region is the surface of the build member 109. The fusing of the powder layers in fig. 1D occurs on the previously fused layers that characterize the entity of the build member 109.

Fig. 2A and 2B are diagrams illustrating exemplary beam shaping components that operate in real-time at two exemplary points to change the geometry of a laser beam in accordance with aspects of the present disclosure. Referring to fig. 2A-2B, the beam shaping component 200 may include fixed

optical elements

202A, 202B and one or more motorized

optical elements

204A, 204B. The

optical elements

202A, 202B may have a fixed position such that the

optical elements

202A, 202B may not be displaced. Motorized

optical elements

204A, 204B may each include an optical element (e.g., a lens), wherein a motor component (not shown) adjusts the position of the optical element of the motorized optical element (e.g., 204A) over time. Although the exemplary beam shaping component 200 includes two motorized optical elements and two fixed optical elements, any number of such optical elements may be used to generate the desired beam shape. Furthermore, although the

optical elements

202A, 202B and 204A, 204B are shown in circular symbols for convenience and clarity, these elements may take any necessary or suitable physical form. Beam shaping can be achieved by phase plate and free space propagation. As such, beam shaping component 200 may include a plurality of diffractive, reflective and refractive devices, such as diffractive beam splitters, diffractive diffusers, phase plates, lenses, and mirrors. Of course, other mechanisms may additionally or alternatively be used to achieve the desired beam geometry. For the purposes of fig. 2A-2B, light propagating from the laser source is generally represented by lines that move from the laser beam source 210 on the left through various optical elements in one or both directions (e.g., depending on whether the light or portions thereof are reflected) and terminate in a desired pattern on the surface of the printed object on the right side of the figure (omitted for clarity).

As shown in fig. 2A, light from the laser beam source 210 may be applied to the stationary optical element 202A. When the laser beam is initially applied to the optical element 202A, the laser beam may thereafter be alternately reflected and refracted via the stationary optical element (e.g., 202A, 202B) and the currently stationary motorized optical element (204A, 204B), thereby producing the first laser spot 206. In fig. 2B, the motorized

optical elements

204A, 204B may thereafter be repositioned such that the geometry of the generated laser beam may be changed to line 208. The size and geometry of the laser beam can be adjusted by displacement of motorized optical elements. That is, a motorized or otherwise automated mechanism that may be included in each motorized

optical element

204A, 204B may be used to control the propagation space between the optical elements so that the final beam size and shape may be modified to a desired form.

Fig. 3 is a diagram illustrating an exemplary L-BPF system for scanning a build member in accordance with aspects of the present disclosure. Referring to fig. 3, a laser beam source 302 may provide a laser beam to a beam shaping component 304. In this example, beam shaping component 304 may be configured similar to beam shaping component 200 (fig. 2A). However, other mechanisms may additionally or alternatively be used to adjust the geometry of the laser beam. The beam shaping component 304 can modify the laser beam provided by the laser beam source 302 to generate a laser spot in the form of a line 306. The modified laser beam source 302 may be directed toward a deflector 305 that applies a modified laser beam 306 to the powder surface. For example only, the modified laser beam 306 may be configured in the form of a line having a length of 10mm and a width of 0.2 mm. The laser beam 306 may be applied to a powder bed 308 supported by a matrix plate 310. For example, the laser beam 306 may be scanned across the region of the powder bed in a direction perpendicular to the line 306 to fuse the powder material in the powder bed 308 to form a slice or layer of the build member according to the design profile. Here, by adjusting the geometry of the laser beam 306 to a line form rather than a dot form, the build up may be improvedRate and can reduce production time. For example, with an exemplary laser beam, moving at 1200m/s perpendicular to its length, the L-BPF process may have 2000cm over a layer thickness of 0.05mm ³ Build rate per h.

In some aspects, the shape of the laser beam may be adjusted based on the desired geometry of the part to be built. Referring to fig. 4, the shape of the laser beam may be adjusted such that the final laser spot is a line. The length of the laser spot lines (e.g., 402A, 402B, and 402C) may be continuously modified (e.g., under control of the beam shaping component 104) based on the geometric boundaries of the part (e.g., build member) to be built. At the first portion, the length of the laser spot line 402A may be a maximum Lmax. Based on the geometry of the build given by the specified geometrical boundaries of the part, the length of the laser spot can be adjusted so that powder outside the geometrical boundaries is not processed. Thus, as shown in fig. 4, as the laser beam continues to scan the powder material in a direction perpendicular to its length, the length of the laser beam may be continuously altered (e.g., tapered) to follow the geometric boundaries of the part until reaching the second portion. At the second portion, the laser beam 402B may be less than L _max Length L of (2) ₁ . As scanning continues, the length of the laser beam may be further adjusted (e.g., gradually increased) until a third portion of the build member is reached. At the third portion, the length of the laser beam 402C may be increased to a length L ₂ . In some aspects, the power (P) of the laser may also be adjusted so that the ratio of laser power to length may be maintained so that the total energy flux remains constant during the scan.

FIG. 5 is a diagram illustrating an example energy flux level configuration of a laser beam tuned for 2-D scanning. As described above, the laser beam may be converted to have a substantially one-dimensional (1-D) shape (approximated by lines) or a two-dimensional (2-D) shape. The beam shape in the 2-D scan may take any 2-D shape including, but not limited to, rectangular, triangular, or other polygonal or geometric shape. Lower energy levels may be applied to the 1-D or 2-D shaped portions. In one example, applying laser beams having different energy levels to different portions of the 2-D shape may be used to provide preheating of the powder material and/or provide cooling rate control based on the relative direction of the laser beams with respect to the peak energy flux zone.

Referring to fig. 5, an energy flux level configuration is provided for three exemplary rectangular laser beam shapes 502A, 502B, and 502C. Rectangular laser beam 502A is divided into four partitions. Each partition may be configured to have a different size with a different energy flux level. For example only, a rectangular laser spot may be configured to be 10mm in length and 5mm in width, with different energy levels across its width. Of course, the number and size of the partitions are merely exemplary, and any number and size of partitions may be included in the laser beam shape. Similarly, although the beam shape in the example of fig. 5 is rectangular, any multi-dimensional shape may be used. In other embodiments, each portion 504A, 504B, etc. may represent a separately tuned geometric beam shape with a particular power applied.

In shaping the laser beam, the energy distribution may be configured such that the energy level may be adjusted along the width of the rectangle. In zone 504A, the energy flux level may be increased to a level sufficient to melt the powder material (e.g., peak energy flux). Thereafter, in

partitions

504B, 504C, and 504D, the energy flux level is continuously reduced in each partition. Thus, rectangular beam shape 502A may provide localized preheating of the powder material when applied in a scan. That is, as the rectangular beam shape 502A scans the powder material in the powder bed (proceeding horizontally in a left-to-right direction), the 2-D scan may progressively heat the powder in the region of the powder bed where 504D is applied first at the lowest energy flux level. When each successive zone is applied to the same region of powder material, the energy flux level (e.g., laser beam intensity) may increase, and the temperature of the powder material may in turn increase. By configuring the energy distribution of the laser beam to preheat the powder material prior to heating the powder to melting, thermal fluctuations and ultimately thermal stresses can be reduced.

In rectangular laser beam shape 502B, four partitions with different energy flux levels are shown. As the laser beam shape 502B scans the powder material in a zone of the powder bed, the energy flux level applied to the powder may gradually decrease. For example, the zone 506D may be applied to a zone of the powder bed 510 to melt the powder material in that zone. As the laser beam continues from left to right in a direction perpendicular to the width of laser beam 502B, progressively lower energy flux levels may be applied as

zones

506C, 506B, and 506A are applied to sequentially scan the material in the zone. By configuring the energy distribution for laser beam shape 502B in this way, 2-D scanning with laser beam 502B may provide control of the cooling rate of the solidified material. Controlling the cooling rate may reduce thermal stresses and further enable the final microstructure of the build member to be produced to a desired performance.

In some aspects, the laser beam may be configured with an energy distribution to provide localized heating and cooling rate control of the powder material after the powder material is melted. As shown in fig. 5, rectangular laser beam 502C includes seven partitions. When applied to the powder material in the region of the powder bed 510, the zones 508G, 508F, 508E progressively heat the powder material in the region prior to melting as the zone 508D scans the region. After the section 508D scans the designated area of the powder bed 510, the

sections

508C, 508B, and 508A may be sequentially applied to gradually reduce the applied energy flux level, thereby controlling the cooling rate of the molten material. Accordingly, the energy fluence level of the laser beam (e.g., 502A, 502B, or 502C) can be adjusted depending on the material being processed to reduce thermal stresses typically observed in parts manufactured by the L-PBF process.

Fig. 6 is a flow chart of an exemplary method of configuring a laser beam in an L-PBF device to scan a build member. The L-PBF device may optionally determine the geometry of the defined build member (602). The L-PBF device may adjust the geometry of the laser beam to form an adjusted laser beam that includes a line or 2-D shape (604). For example, referring to fig. 2A-2B, the beam shaping component 200 may receive a laser beam from a laser beam source. The beam shaping part 200 may be configured with fixed optical elements (202A, 202B) and motorized optical elements (204A, 204B). The motorized optical element (204A, 204B) may be moved or repositioned relative to the fixed optical element (202A, 202B) to control the propagation space between the optical elements (e.g., motorized optical element and fixed optical element) so that the final laser beam size and shape may be altered. Alternative techniques for adjusting the desired laser beam shape may also be possible.

In some aspects, the geometry of the laser beam may be varied during application of the laser beam. For example, as shown in fig. 4, the laser beam adjusted to the form of lines (e.g., 402A, 402B, and 402C) may be continuously altered as the laser beam scans the powder material to generate the build member. In the example of fig. 4, the length of the laser spot line is altered as the scan is performed over the powder bed. However, the present disclosure is not limited thereto, and other modifications are conceivable. For example, the shape of the beam may also be adjusted as the scan proceeds. That is, the laser beam may be formed into a rectangle during one portion of the scan, and may be changed into a triangle at another portion of the scan later. In some aspects, the laser beam (610) may be adjusted based on the geometry of the defined build member. For example, the geometry of the desired build may be analyzed to determine the geometry that may be most effectively (e.g., such that the completion time may be reduced or optimized) used to scan the desired build. In another example, as shown in FIG. 4, the length of the laser spot line is adjusted based on the boundaries specified for the part being built.

In some aspects, the laser beam geometry may be adjusted based on an energy distribution associated with the part being built (608). For example, the melting point may be varied based on the type of powder material (e.g., different metals) used for the desired build. The adjusted laser beam geometry may be divided into zones. The energy distribution may specify different energy flux levels to be applied via each different partition of the adjusted laser beam. For example, as shown in fig. 5, rectangular laser beam 502A may be configured with four partitions. In each of the

zones

504B, 504C, and 504D, the applied energy flux level decreases continuously. Thus, rectangular beam 502A gradually heats the powder when applied to the powder (in reverse order). When each successive zone (e.g., 504d→504c→504b→504A) is applied to the same region of powder material, the energy flux level (e.g., laser beam intensity) can be increased, and the temperature of the powder material can in turn be increased. By adjusting the laser beam with the partitions based on the energy distribution, the laser beam may be configured to preheat the powder material (via partition 504A) before heating the powder to melt. Thus, thermal fluctuations and final thermal stresses in the final construction may be reduced.

In addition, the energy distribution may be used to adjust the laser beam to provide cooling control after the powder material melts. For example, as shown in fig. 5, rectangular laser beam 502B may be tuned and configured to include four zones with different energy flux levels. As rectangular laser beam 502B scans the powder material in the zones of the powder bed, the energy flux level applied to the powder in each zone of the laser beam may be gradually reduced. By controlling the cooling rate, thermal stresses in the final build may be further reduced.

The L-PBF device may apply an adjusted laser beam to at least a portion of the powder material to scan at least a portion of the defined build member (606). For example, as shown in FIG. 3, a laser beam, adjusted to the form of a line (306), is applied to the powder material in the powder bed 308, thereby melting the powder material to define a portion of the build member. The adjusted laser beam may be applied in a direction perpendicular to its length (e.g., a line) or its width. In this way, the adjusted laser beam can be applied to a larger area during scanning, thereby reducing production time.

In some aspects, the geometry of the laser beam may be adjusted based on the temperature profile (612). For example, the temperature profile may include a temperature at which the powder material for the build member melts, as well as other thresholds (e.g., a temperature at which the powder material evaporates). A temperature sensor (such as temperature sensor 122A of fig. 1A) may monitor the temperature of the powder material in the powder bed. When the temperature reaches the critical point, the laser beam may be adjusted (e.g., the energy flux of the laser beam is reduced).

In other embodiments, the 2-D shape may be amorphous, asymmetric, and need not be in the form of a known shape. In some embodiments, CAD software or an application working in conjunction with CAD software may determine the optimal sequence of changing shapes based on the time spent in the 3-D print job. The software may take into account some or all of the factors described above, including temperature distribution, areas where pre-heating and/or pre-cooling is advantageous, geometry of the build object, expectations to minimize evaporation effects, etc., among other variables. The beam shaping component 104 (fig. 1) may be constructed using the various hardware elements mentioned herein and implemented in a 3-D printer to adjust the geometry of the beam. The beam shaping component 104 may be configured to change the beam shape over time, such as continuously changing the length of the beam shape in the form of a line. Continuously moving motorized lenses and other optical elements in conjunction with a stationary element may help provide the ability to change the beam shape over time. CAD software and/or application software associated therewith may be used as a data model for providing instructions to the 3-D printer to operate the beam shaping part 104 and the power distribution of the laser beam source 103 in a manner that imparts a desired result to a given build member.

While the laser beam source 103 and the beam shaping component 104 are generally identified as separate components, in some exemplary embodiments, the functionality of both components may be included as part of a single integrated structure without departing from the scope of the present disclosure.

Various exemplary embodiments disclosed herein are directed to novel configurations of lasers with variable beam geometries in L-PBF systems.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these exemplary embodiments presented throughout this disclosure will be readily apparent to those skilled in the art, and the concepts disclosed herein may be applied to other support structures and systems and methods for removing support structures. Thus, the claims are not intended to be limited to the example embodiments presented throughout this disclosure, but are to be accorded the full scope consistent with the language claims. All structural and functional equivalents to the elements of the exemplary embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The claim element must not be construed in accordance with the terms of 35 u.s.c. ≡112 (f) or similar laws in applicable jurisdictions unless the phrase "means for … …" is used to explicitly recite the element or in the case of a method claim the phrase "step for … …" is used to recite the element.

Claims

1. An apparatus for laser-based powder bed fusion, comprising:

a depositor that deposits a plurality of layers of powder material;

a laser beam source that generates a laser beam; and

a beam shaping component that shapes the laser beam into one of a plurality of beam geometries to fuse the powder material.

2. The apparatus of claim 1, wherein the beam shaping component is configured to change a beam geometry of a laser beam from the laser beam source during application of the laser beam.

3. The apparatus of claim 1, wherein the laser beam geometry is varied based on a design profile of the object to be produced.

4. The apparatus of claim 1, wherein the laser beam geometry is varied based on an energy distribution of the object to be produced.

5. The apparatus of claim 1, wherein the beam geometry of the laser beam comprises a two-dimensional shape.

6. The apparatus of claim 1, wherein the beam geometry of the laser beam comprises a line.

7. The apparatus of claim 6, wherein the length of the line is variable based on an energy distribution of the laser beam.

8. The apparatus of claim 1, wherein the beam geometry comprises at least a first portion and a second portion, and an energy distribution of the first portion is different than an energy distribution of the second portion.

9. The apparatus of claim 8, wherein the energy distribution of the first portion and the energy distribution of the second portion are configured based at least in part on a temperature distribution.

10. The apparatus of claim 8, wherein the laser beam source is configured to provide a constant fluence between the first portion and the second portion.

11. The apparatus of claim 8, wherein the first portion is configured to preheat a powder material and the second portion is configured to fuse the powder material.

12. The apparatus of claim 8, wherein the first portion is configured to fuse powder material and the second portion is configured to reduce energy flux to control cooling of the fused powder material.

13. The apparatus of claim 1, further comprising a controller coupled to the laser beam source and configured to control a power density of a laser beam emitted from the laser beam source.

14. The apparatus of claim 1, wherein the laser beam geometry is varied based on a temperature profile of the object to be produced.

15. The apparatus of claim 1, wherein the beam shaping component comprises at least one of each of a fixed optical element and a movable optical element aligned to enclose the laser beam.

16. The apparatus of claim 15, wherein at least one of the optical elements comprises a lens.

17. A method of laser-based powder bed fusion, comprising:

adjusting the geometry of the laser beam to form an adjusted laser beam comprising a line or two-dimensional shape when contacting the surface of a layer of powder material; and

an adjusted laser beam is applied to at least a portion of the layer of powder material to fuse at least a portion of the defined build member.

18. The method of claim 17, further comprising changing a geometry of the laser beam over time during application of the laser beam.

19. The method of claim 17, further comprising changing a geometry of the laser beam based on an energy distribution of an object to be produced.

20. The method of claim 17, wherein the laser beam geometry of the adjusted laser beam comprises a two-dimensional shape.

21. The method of claim 17, wherein the laser beam geometry of the adjusted laser beam comprises a line, the method further comprising applying the adjusted laser beam in a direction perpendicular to a length of the line.

22. The method of claim 21, further comprising varying the length of the line based on the adjusted energy distribution of the laser beam.

23. The method of claim 17, wherein the laser beam geometry of the adjusted laser beam includes at least a first portion and a second portion, and the energy distribution of the first portion is different than the energy distribution of the second portion.

24. The method of claim 23, wherein the energy distribution of the first portion and the energy distribution of the second portion are configured based at least in part on a temperature distribution.

25. The method of claim 23, wherein the energy profile of the first portion and the energy profile of the second portion are configured to provide a constant energy flux between the first portion and the second portion.

26. The method of claim 23, wherein the first portion is configured to preheat the powder material and the second portion is configured to fuse the powder material.

27. The method of claim 23, wherein the first portion is configured to fuse the powder material and the second portion is configured to reduce energy flux to control cooling of the fused powder material.

28. The method of claim 17, further comprising determining a geometry of the defined build member, and wherein the geometry of the laser beam is adjusted based on the geometry of the defined build member.